Radio IC device

ABSTRACT

A radio IC device includes an electromagnetic coupling module includes a radio IC chip arranged to process transmitted and received signals and a feed circuit board including an inductance element. The feed circuit board includes an external electrode electromagnetically coupled to the feed circuit, and the external electrode is electrically connected to a shielding case or a wiring cable. The shielding case or the wiring cable functions as a radiation plate. The radio IC chip is operated by a signal received by the shielding case or the wiring, and the answer signal from the radio IC chip is radiated from the shielding case or the wiring cable to the outside. A metal component functions as the radiation plate, and the metal component may be a ground electrode disposed on the printed wiring board.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to radio IC devices, and particularly to a radio IC device including a radio IC used for an RFID (Radio Frequency Identification) system.

2. Description of the Related Art

A RFID system has been developed for commodity management in recent years. In the RFID system, information is transmitted by non-contact communication between a reader/writer that generates an induction field and an IC chip (may be referred to as IC tag or radio IC chip) which stores commodity information and other information attached on the package or other item of the commodity.

Japanese Unexamined Patent Application Publication No. 2002-232221 discloses a transmitter/receiver unit including an IC chip-including radio IC device together with other chip components. In the transmitter/receiver unit, a circuit board on which the IC chip is mounted is enclosed in a shielding case, and an antenna element is further disposed on the circuit board.

However, since the antenna element is disposed as an independent component different from the radio IC chip within the shielding case, the radio IC device is relatively large and, consequently, the size of the transmitter/receiver unit is increased. In order to avoid the increase in size, the antenna element is miniaturized. However, this reduces the radiation characteristics of the antenna element, which causes problems, such as a decrease in communication distance.

SUMMARY OF THE INVENTION

To overcome the problems described above, preferred embodiments of the present invention provide a radio IC device that is miniaturized without reducing the radiation characteristics.

A radio IC device according to a preferred embodiment of the present invention includes a high frequency device defined by an electromagnetic coupling module or a radio IC chip, and a radiation plate arranged so as to be coupled to the high frequency device. The electromagnetic coupling module includes a radio IC arranged to process transmitted and received signals and a feed circuit board including a feed circuit having an inductance element connected to or electromagnetically coupled to the radio IC and coupled to an external circuit. The radiation electrode is preferably defined by a case of an apparatus and/or a metal component disposed in the apparatus, for example.

More specifically, the radio IC device includes a high frequency device and a radiation plate, and the high frequency device includes an electromagnetic coupling module or a radio IC chip. The electromagnetic coupling module may preferably include a feed circuit board including the radio IC, or a feed circuit board on which the radio IC is disposed. If the high frequency device is a radio IC chip, the radio IC chip and the radiation plate are coupled to each other with a coupling electrode, such as a loop electrode.

The metal component defining the radiation plate can be any metal portion, such as a wiring electrode disposed in an apparatus, a shielding case, a ground electrode, and a metal portion of a connector, or a metal case of a switching module used in the apparatus, for example.

The feed circuit board may preferably include a resonance circuit and/or a matching circuit. The radio IC is operated by a signal received by the radiation plate through the resonance circuit and/or the matching circuit, and the answer signal from the radio IC is radiated from the radiation plate to the outside through the resonance circuit and/or the matching circuit.

Since the case of the apparatus and/or any metal component in the apparatus can be used as the radiation plate, another component is not required to be provided as an antenna element. Consequently, the size of the apparatus is not increased. In addition, the metal components, such as the case, the wiring electrode, and the ground electrode are relatively large, and accordingly, desired radiation characteristics can be obtained. The apparatus used herein preferably refers to an electronic apparatus in which the radio IC device is to be mounted, such as cellular phone, for example. If the case of the apparatus is a shielding case made of a metal, the case can function as the radiation plate by itself. If the case is made of a non-conductive material, an electroconductive electrode film can be formed on the case so that the electrode film functions as the radiation plate.

In the radio IC device, a miniature radio IC chip can easily be mounted on a small feed circuit board by providing an electromagnetic coupling module including a radio IC chip disposed on a feed circuit board. If the radio IC is modified according to the working frequency of the RFID system, all that is required is to modify the design of the feed circuit of the feed circuit board. It is not necessary to change the shape, size or arrangement of the radiation plate or the coupling state between the radiation plate and the feed circuit board.

The radio IC device according to preferred embodiments of the present invention does not require that an antenna element be disposed as an additional independent component. Thus, the radio IC device and apparatuses including the radio IC device can be miniaturized without degrading the radiation characteristics. The feed circuit board can have a relatively small size. Accordingly, even a very small radio IC chip can be easily mounted on the small feed circuit board with a conventionally used IC mounter. Consequently, the packaging cost is reduced. All that is required to change the working frequency is to modify the design of the feed circuit.

Other features, elements, steps, characteristics and advantages of the present invention will become more apparent from the following detailed description of preferred embodiments of the present invention with reference to the attached drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a sectional view of a radio IC device according to a preferred embodiment of the present invention.

FIG. 2 is a sectional view showing the connection between an electromagnetic coupling module and a wiring electrode.

FIG. 3 is a perspective view of a radio IC chip.

FIG. 4 is a perspective view showing the connection between the wiring electrode and a case.

FIG. 5 is a sectional view of a radio IC device according to another preferred embodiment of the present invention.

FIG. 6 is a perspective view showing the connection from an electromagnetic coupling module and a wiring case.

FIG. 7 is an exploded perspective view of a feed circuit board including a resonance circuit according to a preferred embodiment of the present invention.

FIG. 8 is a plan view a feed circuit board including a resonance circuit according to another preferred embodiment of the present invention.

FIG. 9 is a perspective view of a radio IC device according to another preferred embodiment of the present invention.

FIG. 10 is a perspective view of a radio IC device according to another preferred embodiment of the present invention.

FIG. 11 is a perspective view of a radio IC device according to another preferred embodiment of the present invention.

FIG. 12 is a perspective view of a radio IC device according to another preferred embodiment of the present invention.

FIG. 13 is a perspective view of a radio IC device according to another preferred embodiment of the present invention.

FIG. 14 is a perspective view of a radio IC device according to another preferred embodiment of the present invention.

FIG. 15 is a perspective view of a radio IC device according to another preferred embodiment of the present invention.

FIG. 16 is a perspective view of a radio IC device according to another preferred embodiment of the present invention.

FIG. 17 is an exploded perspective view of a radio IC device according to another preferred embodiment of the present invention.

FIG. 18 is a perspective view of the preferred embodiment shown in FIG. 17.

FIG. 19 is a sectional view of the preferred embodiment shown in FIG. 17.

FIG. 20 is a perspective view of a radio IC device according to another preferred embodiment of the present invention.

FIG. 21 is a perspective view of a radio IC device according to another preferred embodiment of the present invention.

FIG. 22 is a perspective view of a radio IC device according to another preferred embodiment of the present invention.

FIG. 23 is a plan view of a radio IC device according to another preferred embodiment of the present invention.

FIG. 24 is a plan view of the radio IC device according to the preferred embodiment shown in FIG. 23 in the course of manufacture.

FIG. 25 is a plan view of a radio IC device according to another preferred embodiment of the present invention.

FIG. 26 is a plan view of a radio IC device according to another preferred embodiment of the present invention.

FIG. 27 is a plan view of a radio IC device according to another preferred embodiment of the present invention.

FIG. 28 is a plan view of a radio IC device according to another preferred embodiment of the present invention.

FIG. 29 is a plan view of a radio IC device according to another preferred embodiment of the present invention.

FIG. 30 is a plan view of a radio IC device according to another preferred embodiment of the present invention.

FIG. 31 is a plan view illustrating the operation principle of the radio IC device according to the preferred embodiment shown in FIG. 30.

FIG. 32 is a sectional view taken along line A-A in FIG. 30.

FIG. 33 is a sectional view of a radio IC device according to another preferred embodiment of the present invention.

FIG. 34 is a sectional view of a radio IC device according to another preferred embodiment of the present invention.

FIG. 35 is a sectional view of a radio IC device according to another preferred embodiment of the present invention.

FIG. 36 is an assembly diagram of a radio IC device according to another preferred embodiment of the present invention.

FIG. 37 is a plan view of a radio IC device according to another preferred embodiment of the present invention.

FIG. 38 is a plan view of a radio IC device according to another preferred embodiment of the present invention.

FIG. 39 is a plan view of a radio IC device according to another preferred embodiment of the present invention.

FIG. 40 is a plan view of a radio IC device according to another preferred embodiment of the present invention.

FIG. 41 is a plan view of a radio IC device according to another preferred embodiment of the present invention.

FIG. 42 is a plan view of a radio IC device according to another preferred embodiment of the present invention.

FIG. 43 is a plan view of a radio IC device according to another preferred embodiment of the present invention.

FIG. 44 is a plan view of a radio IC device according to another preferred embodiment of the present invention.

FIG. 45 is a sectional view taken along line B-B in FIG. 44.

FIG. 46 is a sectional view of a radio IC device according to another preferred embodiment of the present invention.

FIG. 47 is a sectional view of a radio IC device according to another preferred embodiment of the present invention.

FIG. 48 is a plan view of a radio IC device according to another preferred embodiment of the present invention.

FIG. 49 is a plan view of a radio IC device according to another preferred embodiment of the present invention.

FIG. 50 is a plan view of a radio IC device according to another preferred embodiment of the present invention.

FIG. 51 is a plan view of a radio IC device according to another preferred embodiment of the present invention.

FIG. 52 is a plan view of a radio IC device according to another preferred embodiment of the present invention.

FIG. 53 is a plan view of a radio IC device according to another preferred embodiment of the present invention.

FIG. 54 is a plan view of a radio IC device according to another preferred embodiment of the present invention.

FIG. 55 is a sectional view taken along line C-C in FIG. 54.

FIG. 56 is a plan view of a radio IC device according to another preferred embodiment of the present invention.

FIG. 57 is a plan view of a radio IC device according to another preferred embodiment of the present invention.

FIG. 58 is a plan view of a radio IC device according to another preferred embodiment of the present invention.

FIG. 59 is a plan view of a radio IC device according to another preferred embodiment of the present invention.

FIG. 60 is a plan view of a radio IC device according to another preferred embodiment of the present invention.

FIG. 61 is a plan view of a radio IC device according to another preferred embodiment of the present invention.

FIG. 62 is a plan view of a radio IC device according to another preferred embodiment of the present invention.

FIG. 63 is a plan view illustrating the operation principle of the radio IC device according to the preferred embodiment shown in FIG. 62.

FIG. 64 is a perspective view of an electromagnetic coupling module of the radio IC device according to the preferred embodiment shown in FIG. 62.

FIG. 65 is a sectional view of the electromagnetic coupling module shown in FIG. 62.

FIG. 66 is a plan view of a radio IC device according to another preferred embodiment of the present invention.

FIG. 67 is a plan view of a radio IC device according to another preferred embodiment of the present invention.

FIG. 68 is a plan view of a radio IC device according to another preferred embodiment of the present invention.

FIG. 69 is a plan view of a radio IC device according to another preferred embodiment of the present invention.

FIG. 70 is a plan view of a radio IC device according to another preferred embodiment of the present invention.

FIG. 71 is a plan view of a radio IC device according to a 55th preferred embodiment of the present invention.

FIG. 72 is a plan view of a radio IC device according to another preferred embodiment of the present invention.

FIG. 73 is a plan view of an electromagnetic coupling module of the radio IC device according to the preferred embodiment shown in FIG. 73

FIG. 74 is a plan view of an electromagnetic coupling module according to a modification of a preferred embodiment, used in a radio IC device according to the present invention.

FIG. 75 is a plan view of a radio IC device according to another preferred embodiment of the present invention.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

Preferred embodiments of the radio IC device according to the present invention will now be described with reference to the attached drawings. The same elements and portions in the drawings are designated by the same reference numerals, and the same description is not repeated.

First Preferred Embodiment

FIG. 1 shows portions of an electronic apparatus including a radio IC device according to a first preferred embodiment of the present invention. The electronic apparatus includes a printed wiring board 20 on which an electromagnetic coupling module 1 and other electronic components 26, such as a chip resistor and a chip capacitor, for example, are mounted. The printed wiring board also includes a shielding electrode 27 therein.

The electromagnetic coupling module 1 preferably includes a radio IC chip 5 processing a transmitted/received signal having a predetermined frequency and a feed circuit board 10 on which the radio IC chip 5 is disposed, as shown in FIG. 2. A shielding case 28 of an apparatus also defines a radiation plate that functions as an antenna element, and is electrically connected to second wiring electrodes 21 a and 21 b (see FIGS. 2 and 4) magnetically coupled to the electromagnetic coupling module 1 on the printed wiring board 20. The electromagnetic coupling module 1 and the radiation plate (shielding case 28) define the radio IC device.

The radio IC chip 5 preferably includes a clock circuit, a logic circuit, a memory circuit and other circuit elements, and stores necessary information. On the rear surface of the radio IC chip, input/output terminal electrodes 6 and packaging terminal electrodes 7 are disposed, as shown in FIG. 3. The input/output terminal electrodes 6 are electrically connected to electrodes 12 a and 12 b (see FIGS. 7 and 8) disposed on the surface of the feed circuit board 10 preferably through metal bumps 8, for example. The packaging terminal electrodes 7 are electrically connected to electrodes 12 c and 12 d through the metal bumps 8. The material of the metal bumps 8 can preferably be Au, Ag, solder or other suitable material, for example.

A protective film 9 is provided between the surface of the feed circuit board 10 and the rear surface of the radio IC chip 5 to improve the bonding strength between the feed circuit board 10 and the radio IC chip 5 and to protect the bumps 8.

The shielding case 28 is preferably made of a metal and arranged so as to cover the electromagnetic coupling module 1 and the electronic components 26 on the printed wiring board 20. In addition, the shielding case functions as a radiation plate of the electromagnetic coupling module 1, as will be described below. If the case 28 is made of a nonconductive material, an electroconductive electrode film 28′ is preferably formed on the internal surface of the case 28, as indicated by oblique lines shown in FIG. 4, and the electrode film 28′ functions as the radiation plate.

The feed circuit board 10 includes a feed circuit (including a resonance circuit having an inductance element and a matching circuit, not shown in FIG. 2), and is provided with external electrodes 19 a and 19 b from the rear surface to the sides. Also, the connection electrodes 12 a and 12 d (see FIGS. 7 and 8) are provided on the surface of the feed circuit board 10. The external electrodes 19 a and 19 b are electromagnetically coupled to the resonance circuit included in the feed circuit board 10 and electrically connected to the second wiring electrodes 21 a and 21 b with an electroconductive adhesive 29. The electrical connection may preferably be established by soldering, for example.

More specifically, the feed circuit board 10 includes a resonance circuit having a predetermined resonance frequency that transmits a signal having the predetermined frequency generated from the radio IC chip 5 to the shielding case 28 (or the electrode film 28′) through the external electrodes 19 a and 19 b and the wiring electrodes 21 a and 21 b, and supplies a signal having the predetermined frequency selected from the signals received by the shielding case 28 (or the electrode film 28′) to the radio IC chip 5. In the radio IC device, the radio IC chip 5 operates according to the signal received by the shielding case (or the electrode film 28′), and an answer signal from the radio IC chip 5 is radiated from the shielding case 28 (or the electrode film 28′).

In the electromagnetic coupling module 1, the external electrodes 19 a and 19 b disposed on the surface of the feed circuit board 10 are electromagnetically coupled to the resonance circuit included in the feed circuit board 10 and electrically connected to the shielding case 28 which functions as an antenna. The electromagnetic coupling module 1 does not require a separate, relatively large antenna element, and accordingly the electromagnetic coupling module can be very small. Since the feed circuit board 10 has been miniaturized, the radio IC chip 5 can preferably be mounted on a miniaturized feed circuit board 10 by a conventionally used IC mounter or other suitable mounter, for example, and thus, the packaging cost can be reduced. All that is required to change the working frequency is to modify the design of the feed circuit, and the shielding case 28 may be used without being modified. The shielding case 28 is relatively large and can ensure desired radiation characteristics.

Preferably, the electroconductive adhesive 29 used to bond the external electrodes 19 a and 19 b with the second wiring electrodes 21 a and 21 b includes metal particles. Such an adhesive 29 exhibits a small difference in thermal expansion from the external electrodes 19 and 19 b and the wiring electrodes 21 a and 21 b when undergoing temperature changes, and accordingly, the bonding reliability is improved.

The second wiring electrodes 21 a and 21 b may be provided within the printed wiring board 20. In this instance, the second wiring electrodes 21 a and 21 b are electrically connected to the electrodes on the surface of the wiring board 20 through a known via hole conductor. The printed wiring board 20 may preferably be a ceramic multilayer substrate or a resin substrate, for example.

Second Preferred Embodiment

FIG. 5 shows essential portions of an electronic apparatus including a radio IC device according to a second preferred embodiment of the present invention. The electronic apparatus includes a plurality of printed wiring boards 31 and 32 covered with a case 33. The printed wiring boards 31 and 32 are disposed on a substrate 30. One printed wiring board 31 is provided with an electromagnetic coupling module 1 and other electronic components thereon, and the other printed wiring board 32 is provided with other electronic components thereon.

In the electromagnetic coupling module 1, the external electrodes 19 a and 19 b (see FIG. 2) of the electromagnetic coupling module 1 are electrically connected to second wiring electrodes 21 a and 21 b disposed on the printed wiring board 31, as shown in FIG. 6. The wiring electrodes 21 a and 21 b are connected to one end of a wiring cable 36 defining a first wiring electrode provided to a known wiring connector 35. The other end of the wiring cable 36 is fixed to a securing member 37 disposed on the printed wiring board 32 and is electrically open.

In the second preferred embodiment, the wiring cable 36 between the wiring boards 31 and 32 functions as a radiation plate of the electromagnetic coupling module 1. Thus, an RFID system is defined, and transmits and receives high-frequency signals to and from a reader/writer. Thus, the same effects are produced as in the first preferred embodiment.

First Preferred Embodiment of Resonance Circuit

FIG. 7 shows a resonance circuit according to a first preferred embodiment, in which the feed circuit board 10 includes the resonance circuit. The feed circuit board 10 is preferably prepared by stacking dielectric ceramic sheets 11A to 11H, and pressing and firing the stack. The sheet 11A is provided with connection electrodes 12 a and 12 b, electrodes 12 c and 12 d, and via hole conductors 13 a and 13 b. The sheet 11B is provided with a capacitor electrode 18 a, conductor patterns 15 a and 15 b, and via hole conductors 13 c to 13 e. The sheet 11C is provided with a capacitor electrode 18 b and via hole conductors 13 d to 13 f. The sheet 11D is provided with conductor patterns 16 a and 16 b and via hole conductors 13 e, 13 f, 14 a, 14 b and 14 d. The sheet 11E is provided with conductor patterns 16 a and 16 b and via hole conductors 13 e, 13 f, 14 a, 14 c and 14 e. The sheet 11F is provided with a capacitor electrode 17, conductor patterns 16 a and 16 b and via hole conductors 13 e, 13 f, 14 f and 14 g. The sheet 11G is provided with conductor patterns 16 a and 16 b and via hole conductors 13 e, 13 f, 14 f and 14 g. The sheet 11H is provided with conductor patterns 16 a and 16 b and a via hole conductor 13 f.

By stacking these sheets 11A to 11H, a conductor pattern 16 a is preferably provided in a spiral arrangement, for example, continuing through the via hole conductors 14 c, 14 d and 14 g, thus defining an inductance element L1, and a conductor pattern 16 b is preferably provided in a spiral arrangement, for example, continuing through the via hole conductors 14 b, 14 e and 14 f, thus defining an inductance element L2. Also, a capacitance element C1 is defined by capacitor electrodes 18 a and 18 b, and a capacitance element C2 is defined by capacitor electrodes 18 b and 17.

One end of the inductance element L1 is connected to the capacitor electrode 18 b through the via hole conductor 13 d, conductor pattern 15 a and the via hole conductor 13 c, and one end of the inductance element L2 is connected to the capacitor electrode 17 through the via hole conductor 14 a. The other ends of the inductance elements L1 and L2 are brought together on the sheet 11H and connected to the connection electrode 12 a through the via hole conductor 13 e, the conductor pattern 15 b and the via hole conductor 13 a. In addition, the capacitor electrode 18 a is electrically connected to the connection electrode 12 b through the via hole conductor 13 b.

The connection electrodes 12 a and 12 b are electrically connected to the input/output terminal electrodes 6 (see FIG. 3) of the radio IC chip 5 through the metal bumps 8 (see FIG. 2). The electrodes 12 c and 12 d are connected to the packing terminal electrodes 7 of the radio IC chip 5.

In addition, the external electrodes 19 a and 19 b are provided on the rear surface of the feed circuit board 10 preferably by applying a conductive paste, for example. The external electrode 19 a is coupled to the inductance elements L (L1 and L2) by a magnetic field, and the external electrode 19 b is connected to the capacitor electrode 18 b through the via hole conductor 13 f. The external electrodes 19 a and 19 b are electrically connected to the wiring electrodes 21 a and 21 b, as described above.

In the resonance circuit, the inductance elements L1 and L2 are arranged such that two conductor patterns 16 a and 16 b are disposed in parallel or substantially in parallel. The two conductor patterns 16 a and 16 b preferably have different line lengths from each other so as to have different resonance frequencies. Thus, the radio IC device can be used for a wide range of frequencies.

The ceramic sheets 11A to 11H may be made of a magnetic ceramic material, and the feed circuit board 10 can be easily produced by a known process for forming a multilayer substrate, such as stacking sheets or printing into a thick film, for example.

The sheets 11A to 11H may preferably be flexible sheets made of, for example, a dielectric material such as polyimide or liquid crystal polymer. Electrodes or conductors are formed on such flexible sheets by a thick film forming process, for example, and then the sheets are stacked one on top of another and thermally compressed into a multilayer composite. Thus, the inductance elements L1 and L2 and the capacitance elements C1 and C2 may be disposed within the circuit board.

In the feed circuit board 10, the inductance elements L1 and L2 and the capacitance elements C1 and C2 are disposed at different positions when viewed from above. The inductance elements L1 and L2 are coupled to the external electrode 19 a (wiring electrode 21 a) by a magnetic field, and the capacitance element C1 is coupled to the external electrode 19 b (wiring electrode 21 b) by an electric field.

Thus, the electromagnetic coupling module 1 including the radio IC chip 5 on the feed circuit board 10 receives high-frequency signals (for example, UHF frequencies) radiated from a reader/writer (not shown) with a shielding case 28 or a wiring cable 36, so that the resonance circuit coupled to the external electrodes 19 a and 19 b through the wiring electrodes 21 a and 21 b by a magnetic field and an electric field resonates to supply only a received signal having a predetermined frequency to the radio IC chip 5. A predetermined energy is extracted from the received signal. The energy is used as a driving source to match the information stored in the radio IC chip 5 with a predetermined frequency by a resonance circuit, and to transmit the information to the shielding case 28 or the wiring cable 36 through the external electrodes 19 a and 19 b and the wiring electrodes 21 a and 21 b, and further transmit or transfer the information to the reader/writer from the case 28 or the cable 36.

The resonance frequency characteristics of the feed circuit board 10 depend on the resonance circuit including the inductance elements L1 and L2 and the capacitance elements C1 and C2. The resonance frequency of the signal radiated from the shielding case 28 or the wiring cable 36 substantially depends on the self resonant frequency of the resonance circuit. It is accordingly not necessary to redesign the resonance circuit even if the shielding case 28 or the wiring cable 36 is changed in shape or material. Thus, the resonance circuit can be applied to various electronic apparatuses.

The resonance circuit preferably also defines a matching circuit to match the impedances between the radio IC chip 5 and the radiation plate (shielding case 28 or wiring cable 36). The feed circuit board 10 may preferably include a matching circuit provided in addition to the resonance circuit including the inductance elements and the capacitance elements (in this sense, the resonance circuit may be referred to as matching circuit). The design for a resonance circuit also defining a matching circuit tends to be complicated. A structure in which a matching circuit is provided separately from the resonance circuit enables the resonance circuit and the matching circuit to be independently designed. The resonance circuit may be replaced with a matching circuit. The resonance circuit may be designed in view of the shape and size of the radiation plate, or the shielding case 28 or the wiring cable 36. Although this requires that the feed circuit board 10 be precisely mounted at a correct position, the radiation characteristics of the resulting radio IC device can be improved.

Second Preferred Embodiment of Resonance Circuit

FIG. 8 shows a resonance circuit according to a second preferred embodiment, in which the resonance circuit is disposed on a feed circuit board 40. This feed circuit board 40 is preferably made of a flexible PET film, for example, and on which a spiral conductor pattern 42 defining inductance elements L and a capacitor electrode 43 defining a capacitance element C are disposed. Electrodes 12 a and 12 b extending from the conductor pattern 42 and the capacitor electrode 43 are electrically connected to the terminal electrodes 6 of the radio IC chip 5. Electrodes 12 c and 12 d provided on the circuit board define terminal ground electrodes and are electrically connected to the terminal electrodes 7 of the radio IC chip 5.

The feed circuit board 40 is substantially the same as that of the first preferred embodiment in that the inductance elements L and the capacitance element C define a resonance circuit and are coupled to the respectively opposing second wiring electrodes 21 a and 21 b by a magnetic field and an electric field to transmit and receive a high-frequency signal having a predetermined frequency. In the second preferred embodiment, in particular, the feed circuit board 40 made of a flexible film produces a thin electromagnetic coupling module 1. The inductances of the inductance elements L can be varied by varying the line width and/or the line pitch of the conductor pattern 42, and thus the resonance frequency can be precisely adjusted.

In the second preferred embodiment, the conductor pattern 42 defining the inductance elements L preferably includes two spiral lines that are connected to each other at the approximate center of the spirals. The two lines of the conductor pattern 42 have respective inductances L1 and L2 and their resonance frequencies can be set to different values. Thus, the resulting radio IC device can be used in a wide range of frequencies as that of the first preferred embodiment.

Third Preferred Embodiment

In the radio IC device according to a third preferred embodiment, second wiring electrodes 22 a and 22 b are preferably configured in a meandering arrangement on the printed wiring board 20 of an electronic apparatus. The electromagnetic coupling module 1 is mounted on one end of each of the wiring electrodes 22 a and 22 b, as shown in FIG. 9. A metal case 50 of a battery or liquid crystal panel is disposed close to the electrode 22 b on the printed wiring board 20. The electromagnetic coupling module 1 is coupled to the wiring electrodes 22 a and 22 b in substantially the same manner as in the first and second preferred embodiments.

In the third preferred embodiment, the second wiring electrodes 22 a and 22 b function as the radiation plate, and the metal case 50 via the wiring electrode 22 b is coupled to the wiring electrode 22 b to function as the radiation palate. The wiring electrodes 22 a and 22 b themselves may function as the radiation plate, and, in addition, the metal case 50 is also used as the radiation plate. Consequently, the radiation characteristics and the antenna gain are improved. The radio IC device of the third preferred embodiment can function without the metal case 50. By matching the resonance frequency of the metal case 50 to the working frequency of the radio IC device, the antenna gain can be further improved.

Fourth Preferred Embodiment

The radio IC device according to a fourth preferred embodiment has substantially the same structure as that of the third preferred embodiment, except that a portion of the metal case 50 used in the third preferred embodiment is disposed on the wiring electrode 22 b, as shown in FIG. 10. The fourth preferred embodiment produces substantially the same effects as the third preferred embodiment. Since the metal case 50 overlaps the wiring electrode 22 b, particularly, the degree of their coupling is increased.

Fifth Preferred Embodiment

In the radio IC device according to a fifth preferred embodiment, the wiring electrode 22 a is electrically connected to a ground electrode 23 disposed on the printed wiring board 20, and the other wiring electrode 22 b is disposed close to the metal case 50, as shown in FIG. 11.

The ground electrode 23 may be included in the printed wiring board 20. In this instance, the wiring electrode 22 a may be connected to the ground electrode 23 through a via-hole conductor, or may be configured to have a meandering arrangement as shown in FIG. 9 and overlap the ground electrode 23.

In the fifth preferred embodiment, the wiring electrode 22 b and the metal case 50 function as a radiation plate, and, in addition, the ground electrode 23 connected to the wiring electrode 22 a also function as a radiation plate. Since the ground electrode 23 has a large area, the radiation characteristics and the antenna gain are improved.

Sixth Preferred Embodiment

The radio IC device according to a sixth preferred embodiment has substantially the same structure as that of the fifth preferred embodiment except that a portion of the metal case 50 used in the fifth preferred embodiment is disposed on the wiring electrode 22 b, as shown in FIG. 12. The sixth preferred embodiment produces substantially the same effects as the fifth preferred embodiment. Since the metal case 50 overlaps the wiring electrode 22 b, particularly the degree of their coupling is increased.

Seventh Preferred Embodiment

In the radio IC device according to a seventh preferred embodiment, a loop electrode 24 defining the second wiring electrode is disposed on the printed wiring board 20, and the electromagnetic coupling module 1 is disposed on both ends of the line of the loop electrode 24, as shown in FIG. 13. The metal case 50 is disposed close to the loop electrode 24 on the printed wiring board 20. The electromagnetic coupling module 1 is coupled to the loop electrodes 24 in substantially the same manner as in the first and the second preferred embodiment.

In the seventh preferred embodiment, the loop electrode 24 functions as a radiation plate, and the metal case coupled to the loop electrode 24 also functions as a radiation plate. In particular, the loop electrode 24 can match the impedances between the radio IC chip 5 and the radiation plate, and thus improves the signal transmission efficiency between the radio IC chip 5 and the radiation plate without requiring an additional matching portion.

Eight Preferred Embodiment

In the radio IC device according to an eighth preferred embodiment, the metal case 50 used in the sixth preferred embodiment (see FIG. 12) is disposed on the rear surface of the printed wiring board 20, as shown in FIG. 14. A portion of the metal case 50 is coupled to the wiring electrode 22 b with the printed wiring board 20 therebetween. The other structure is substantially the same as in the sixth preferred embodiment. The eighth preferred embodiment produces substantially the same effects as the sixth preferred embodiment. Since the metal case 50 is disposed on the rear surface of the printed wiring board 20, the ground electrode 23 can be provided with a large area.

Ninth Preferred Embodiment

In the radio IC device according to a ninth preferred embodiment, another metal case 51 is included close to the wiring electrode 22 a on the surface of the printed wiring board 20 of the third preferred embodiment (see FIG. 9), as shown in FIG. 15. The metal case 51 is coupled to the wiring electrode 22 a to function as a radiation plate, and, thus, the antenna gain is further improved.

Tenth Preferred Embodiment

In the radio IC device according to a tenth preferred embodiment, the metal case 51 used in the ninth preferred embodiment is disposed on the rear surface of the printed wiring board 20, as shown in FIG. 16. In this instance, the metal case is coupled to the wiring electrode 22 a with the printed wiring board 20 therebetween.

Eleventh Preferred Embodiment

In the radio IC device according to an eleventh preferred embodiment, the printed wiring board 20 is enclosed by an upper and a lower metal case 52 and 53, as shown in FIGS. 17 and 18, and the metal cases 52 and 53 function as radiation plates. Wiring electrodes 22 a and 22 b are provided on the printed wiring board 20 and coupled to the electromagnetic coupling module 1. The wiring electrode 22 a is disposed on the rear side and connected to the front side through a via hole conductor. The wiring electrode 22 b is disposed on the front side.

As shown in FIG. 19, in addition, the metal case 52 has a coupling conductor 52 a to enable the metal case 52 to couple efficiently to the wiring electrode 22 b, and the metal case 53 has a coupling conductor 53 a to enable the metal case 53 to couple efficiently to the wiring electrode 22 a.

In the eleventh preferred embodiment, the wiring electrodes 22 a and 22 b function as radiation plates, and the metal cases 52 and 53 coupled to the respective wiring electrodes 22 a and 22 b also function as the radiation plates. Thus, the radiation characteristics and the antenna gain are improved.

Twelfth Preferred Embodiment

In the radio IC device according to a twelfth preferred embodiment, a portion of the metal case 50 is disposed on the ground electrode 23 connected to the wiring electrode 22 a as in the fifth preferred embodiment (see FIG. 11), as shown in FIG. 20. The ground electrode 23 and the metal case 50 are coupled to each other to function as a radiation plate.

Thirteenth Preferred Embodiment

In the radio IC device according to a thirteenth preferred embodiment, the area of the loop electrode 25 provided as the second wiring electrode is increased as shown in FIG. 21 so that the loop electrode 25 can be used as a ground electrode 23 or a power supply electrode. The metal case 50 is disposed on a portion of the loop electrode 25. In the thirteenth preferred embodiment, the loop electrode 25 and the metal case 50 function as a radiation plate.

Fourteenth Preferred Embodiment

In the radio IC device according to a fourteenth preferred embodiment, the loop electrode 25 provided as the second wiring electrode and the ground electrode 23 are integrated to function as a radiation plate, and a metal case 54 electrically connected to the ground electrode 23 is disposed on the printed wiring board 20 so as to cover the radiation plate, as shown in FIG. 22. The metal case 54 has a notch 55 in a region corresponding to the loop electrode 25 when viewed from above. Since a magnetic field is generated around the loop electrode 25, the magnetic field is radiated out of the metal case 54 through the notch 55 over the loop electrode 25. Thus, the radiation characteristics are improved. The metal case 54 may be disposed so as to cover at least one of other electronic components (not shown).

Fifteenth Preferred Embodiment

In the radio IC device according to a fifteenth preferred embodiment, a ground electrode 101 including an opening 102 is disposed on a printed wiring board 100, and a pair of loop electrodes 103 functioning as inductance elements are provided in the opening 102, as shown in FIG. 23. The electromagnetic coupling module 1 (or radio IC chip 5 alone) is coupled to the end of each loop electrode 103. The printed wiring board 100 includes switching modules 105, ICs 106, and other elements 107, such as chip resistors and chip capacitors thereon. The printed wiring board 100 is covered with a shielding case 109.

A USB connector 110 is connected to the printed wiring board 100. The metal portion of the connector 110 is electrically connected to the ground electrode 101 and functions as a radiation plate of the electromagnetic coupling module 1. The ground electrode 101 includes a slit 104 in the vicinity of the connector 110, so that electromagnetic waves through the connector 110 can efficiently propagate to the loop electrodes 103.

FIG. 24 shows a state before the shielding case 109 and the connector 110 are disposed on the printed wiring board 100. In this state, the ground electrode 101 functions as a radiation plate. Thus, the structure of the fifteenth preferred embodiment can function as a radio IC device from a stage shown in FIG. 24 to the final stage shown in FIG. 23 of the manufacturing process.

Sixteenth Preferred Embodiment

In the radio IC device according to a sixteenth preferred embodiment, the shielding wire 111 a of a coaxial cable (power supply cable) 111 is electrically connected to the ground electrode 101 disposed on the printed wiring board 100, as shown in FIG. 25. The other structure is substantially the same as in the fifteenth preferred embodiment.

In the sixteenth preferred embodiment, the shielding wire 111 a of the coaxial cable 111 electrically connected to the ground electrode 101 functions as a radiation plate of the electromagnetic coupling module 1. Since the shielding wire 111 a is relatively long, communication can be performed even with weak electromagnetic waves.

Seventeenth Preferred Embodiment

In the radio IC device according to a seventeenth preferred embodiment, a slot case 112 of a USB card is electrically connected to the ground electrode 101 disposed on the printed wiring board 100, as shown in FIG. 26. The other structure is substantially the same as in the fifteenth preferred embodiment. The slot case 112 is a metal component, and is electrically continued to the ground electrode 101 to function as a radiation plate of the electromagnetic coupling module 1.

Eighteenth Preferred Embodiment

In the radio IC device according to an eighteenth preferred embodiment, the metal case of a battery 113 is electrically connected to the ground electrode 101 disposed on the printed wiring board 100, as shown in FIG. 27. The other structure is substantially the same as in the fifteenth preferred embodiment. The metal case of the battery 113 is electrically connected to the ground electrode 101 to function as the radiation plate of the electromagnetic coupling module 1.

Nineteenth Preferred Embodiment

In the radio IC device according to a nineteenth preferred embodiment, the shielding case 109 of the fifteenth preferred embodiment shown in FIG. 23 is electrically connected to the ground electrode 101 through a conductor portion 109 a, as shown in FIG. 28. The other structure is substantially the same as in the fifteenth preferred embodiment. In the nineteenth preferred embodiment, the shielding case 109 as well as the metal portion of the connector 110 functions as a radiation plate. The ground electrode 101 includes a slit 104 in the vicinity of the conductor portion 109 a, so that electromagnetic waves through the shielding case 109 can efficiently propagate to the loop electrode 103.

Twentieth Preferred Embodiment

In the radio IC device according to a twentieth preferred embodiment, the shielding case 109 of the sixteenth preferred embodiment shown in FIG. 25 is electrically connected to the ground electrode 101 through a conductor portion 109 a, as shown in FIG. 29. The other structure is substantially the same as in the sixteenth preferred embodiment. In the twentieth preferred embodiment, the shielding case 109 as well as the shielding wire 111 a of the coaxial cable 111 functions as a radiation plate. The ground electrode 101 includes a slit 104 in the vicinity of the conductor portion 109 a, so that electromagnetic waves through the shielding case 109 can efficiently propagate to the loop electrode 103.

Twenty First Preferred Embodiment

In the radio IC device according to a twenty first preferred embodiment, a ground electrode 121 disposed on a printed wiring board 120 includes a slit opening 121 a, as shown in FIG. 30. A wiring electrode (hereinafter referred to as power line 122) is provided in the slit opening 121 a. A power supply cable 128 is connected to the ground electrode 121, and another power supply cable 129 is connected to the power line 122. In this state, the electromagnetic coupling module 1 is bonded on the power line 122. The printed wiring board 120 is covered with a shielding case 127 and the power supply cables 128 and 129 extend a relatively long distance out of the shielding case 127. The power line 122 is provided with a capacitor 125 to reject high-frequency noises, a voltage regulator 126 and other interference to stabilize the voltage.

The electromagnetic coupling module 1 includes a feed circuit board 130 including a coil (inductance element) 131, a radio IC chip 5 on the feed circuit board 130, and a resin protecting member 141 covering the feed circuit board 130 and the radio IC chip 5, as shown in FIG. 32. The coil 131 is arranged such that the coil axis extends parallel or substantially parallel to the power line 122, and each end of which is electrically connected to the radio IC chip 5.

In the operation principle of the radio IC device of the twenty first preferred embodiment, when the power supply cable 129 receives magnetic waves from a reader/writer (not shown), the power line 122 generates a current, as shown in FIG. 31. The current flows to the ground electrode 121 through the capacitor 125 to generate a magnetic field φ at the power line 122. The magnetic field φ is coupled to the coil 131 of the feed circuit board 130, thus operating the radio IC chip 5.

In the twenty first preferred embodiment, the power supply cable 129 functions as a radiation plate. Also, the power line 122 functions as a radiation plate in the course of the manufacturing process in which the shielding case 127 or the power supply cable 129 is not provided. The power supply cable 129 may be directly connected to the reader/writer.

Twenty Second Preferred Embodiment

In the radio IC device according to a twenty second preferred embodiment, the feed circuit board 130 of the electromagnetic coupling module 1 is provided with a matching circuit/resonance circuit 132 in addition to the coil 131, as shown in FIG. 33. The other structure is substantially the same as in the twenty first preferred embodiment. The twenty second preferred embodiment produces substantially the same effects as the twenty first preferred embodiment. In particular, when the circuit 132 is a matching circuit, the matching with the coil 131 can be provided, so that the radio IC chip 5 can be operated even at a low power. When the circuit 132 is a resonance circuit, the radio IC chip can be frequency-selective, and accordingly, the variation in frequency can be reduced. Thus, the radio IC chip can work in a wide range of frequencies.

Twenty Third Preferred Embodiment

In the radio IC device according to a twenty third preferred embodiment, the feed circuit board 130 of the electromagnetic coupling module 1 is provided with a pair of external terminal electrodes 133 on the rear surface thereof, as shown in FIG. 34. The other structure is substantially the same as in the twenty first preferred embodiment. The twenty third preferred embodiment produces substantially the same effects as the twenty first preferred embodiment. In particular, the external terminal electrodes 133 provided on the rear surface of the feed circuit board 130 allow the electromagnetic coupling module 1 to be joined to the power line 122 with solder, for example. Thus, the electromagnetic coupling module 1 can be mounted simultaneously with other surface mount components. Alternatively, only a single external terminal electrode 133 may be formed at substantially the center of the rear surface of the feed circuit board 130.

Twenty Fourth Preferred Embodiment

In the radio IC device according to a twenty fourth preferred embodiment, the feed circuit board 130 of the electromagnetic coupling module 1 is provided with a pair of external terminal electrodes 133 on the rear surface thereof, as shown in FIG. 35. In addition, a conductor 134 is disposed within the feed circuit board 130 on the rear surface side, and the power line 122 is cut under the conductor 134. The other structure is substantially the same as in the twenty first and the twenty third preferred embodiment. The twenty fourth preferred embodiment produces substantially the same effects as the twenty first and the twenty third preferred embodiment. Since the current running in the power line 122 is conducted to flow near the coil 131 by the conductor 134, the degree of coupling is improved, and accordingly, the radio IC chip can operate at a low power. In addition, the variation in coupling degree is reduced.

Twenty Fifth Preferred Embodiment

In the radio IC device according to a twenty fifth preferred embodiment, an auxiliary substrate 140 is provided on which an electromagnetic coupling module 1 is mounted, as shown in FIG. 36. A coupling electrode 141 having an opening 142 is provided on the auxiliary substrate 140, and a pair of loop electrodes 143 functioning as inductance elements is provided in the opening 142. The electromagnetic coupling module 1 (or radio IC chip 5 alone) is coupled to the end of each loop electrode 143. The other structure is substantially the same as in the twenty first preferred embodiment.

In the twenty fifth preferred embodiment, the electromagnetic coupling module 1 is coupled to the loop electrodes 143, and in addition, the coupling electrode 141 is coupled to the power line 122. Substantially the same effects are produced as in the twenty first preferred embodiment. In particular, the use of the auxiliary substrate 140 enables the use of a large coupling electrode 141 or the increase of the coil 131 in the feed circuit board 130. Thus, the degree of coupling to the power line 122 can be increased. In addition, the coupling electrode 141 on the auxiliary substrate 140 can function as the radiation plate by itself, and can be disposed anywhere on the printed wiring board 120.

Twenty Sixth Preferred Embodiment

In the radio IC device according to a twenty sixth preferred embodiment, a power line 122 on which the electromagnetic coupling module 1 is mounted is arranged so as to extend a relatively long distance in the lateral direction along an edge of the printed wiring board 120, as shown in FIG. 37. The other structure is substantially the same as in the twenty first preferred embodiment (see FIG. 30). The twenty sixth preferred embodiment produces substantially the same effects as the twenty first preferred embodiment. The lengthened power line 122 functions as the radiation plate and allows the radio IC device to function before the shielding case 127 or the power supply cable 129 is provided.

Twenty Seventh Preferred Embodiment

In the radio IC device according to a twenty seventh preferred embodiment, the power line 122 shown in FIG. 37 is branched so as to extend a relatively long distance in the lateral direction along an edge of the printed wiring board 120, as shown in FIG. 38. The other structure is substantially the same as in the twenty first and the twenty sixth preferred embodiment. Since the power line 122 functioning as a radiation plate of the twenty seventh preferred embodiment is longer than that of the twenty sixth preferred embodiment, electromagnetic waves can be more efficiently transmitted and received, and the operation can be performed at a low power. Preferably, the power line 122 has a length that enables it to resonate.

Twenty Eighth Preferred Embodiment

In the radio IC device according to a twenty eighth preferred embodiment, the extensions of the power line 122 shown in FIG. 38 are configured in a meandering arrangement, as shown in FIG. 39. The other structure is substantially the same as in the twenty first preferred embodiment. In the twenty eighth preferred embodiment, the power line 122 functioning as a radiation plate is relatively large, and accordingly, electromagnetic waves can be transmitted and received more efficiently.

Twenty Ninth Preferred Embodiment

In the radio IC device according to a twenty ninth preferred embodiment, the ground electrode 121 disposed on the printed wiring board 120 has a relatively large opening 121 b in which a plurality of line electrodes 145 are arranged in parallel or substantially in parallel with each other. The line electrodes 145 are connected to signal lines 146, such as for a USB, and one of which is coupled to the electromagnetic coupling module 1, as shown in FIG. 40. A regulator 126 is disposed between the line electrodes 145 and the ground electrode 121.

In the twenty ninth preferred embodiment, the signal lines 146 functions as a radiation plate, and substantially the same effects are produced as in the twenty first preferred embodiment and other preferred embodiments. In particular, the radio IC device can function even though it is driven by a battery and does not have a power supply cable.

Thirtieth Preferred Embodiment

In the radio IC device according to a thirtieth preferred embodiment, the electrode 121 disposed on the printed wiring board 120 includes a slit opening 121 a, as shown in FIG. 41. An antenna line 151 is disposed in the slit opening 121 a, and an antenna wire 152 is connected to the antenna line 151. The electromagnetic coupling module 1 is coupled to the antenna line 151. The regulator 126 is disposed between the antenna line 151 and the ground electrode 121.

In the thirtieth preferred embodiment, the antenna wire 152 functions as a radiation plate, and substantially the same effects are produced as in the twenty first preferred embodiment and other preferred embodiments. The electromagnetic coupling module 1 is provided with a resonance circuit or a matching circuit so that energy is transmitted to the radio IC chip 5 only at a frequency at which the IC chip 5 operates as an RFID, thus preventing interference with the operation of the antenna. In the present preferred embodiment, the antenna wire 152 intended to receive electromagnetic waves is efficiently used as a radiation plate. Accordingly, the operation can be performed at a low power.

Thirty First Preferred Embodiment

In the radio IC device according to a thirty first preferred embodiment, an anti-ESD device, such as a varistor 153, for example, is disposed between the power line 122 and the ground electrode 121, and the electromagnetic coupling module 1 is disposed downstream from the varistor 153, as shown in FIG. 42. The other structure is substantially the same as in the twenty first preferred embodiment (see FIG. 30). The thirty first preferred embodiment produces substantially the same effects as the twenty first preferred embodiment. In particular, the presence of the varistor 153 improves the electrostatic surge resistance.

Thirty Second Preferred Embodiment

The radio IC device according to a thirty second preferred embodiment is substantially the same as that of the twenty first preferred embodiment (see FIG. 30) in that the electromagnetic coupling module 1 is coupled to the power line 122, as shown in FIG. 43. The two preferred embodiments have a difference in that the coil 131 provided on the feed circuit board 130 is disposed such that the coil axis extends in the direction perpendicular or substantially perpendicular to the power line 122. The thirty second preferred embodiment produces substantially the same effects as the twenty first preferred embodiment. In particular, the coil 131 is arranged such that the coil axis extends in the direction in which the sheets of the feed circuit board 130 are stacked, and this facilitates the formation of the coil 131.

Thirty Third Preferred Embodiment

In the radio IC device according to a thirty third preferred embodiment, the ground electrode 121 disposed on the printed wiring board 120 includes a slit opening 121 a, as shown in FIG. 44. A power line 122 is disposed in the slit opening 121 a. A power supply cable 128 is connected to the ground electrode 121, and another power supply cable 129 is connected to the power line 122. In this state, an electromagnetic coupling module 1 is bonded across the region between the power line 122 and the ground electrode 121. The printed wiring board 120 is covered with a shielding case 127 and the power supply cables 128 and 129 extend long out of the shielding case 127. The power line 122 is provided with a capacitor 125 for rejecting high-frequency noises, a voltage regulator 126 and the like to stabilize the voltage.

The electromagnetic coupling module 1 includes the radio IC chip 5 and a feed circuit board 160, as shown in FIG. 45. The feed circuit board 160 includes inductance elements L11 and L12 magnetically coupled to each other, and a resonance circuit having a predetermined resonance frequency with capacitors defined by an internal electrode 161 and a ground electrode 121 and by an internal electrode 162 and a power line 122. The radio IC chip 5 is electrically connected to the resonance circuit with solder bumps. In FIG. 45, reference numeral 156 designates an adhesive, and reference numeral 166 designates a protective layer for the solder bumps.

In the operation principle of the radio IC device of the thirty third preferred embodiment, when the power supply cable 129 receives magnetic waves from a reader/writer (not shown), the power line 122 generates a current. In this instance, the power line 122 and the ground electrode 121 have a potential difference therebetween, because of the presence of an inductance component (in a coil form) as shown in FIG. 44 in view of high frequency. The occurrence of the potential difference enables the internal electrodes 161 and 162 of the feed circuit board 160 to be electromagnetically coupled to the ground electrode 121 and the power line 122, so that a signal operates the radio IC chip 5 through the resonance circuit.

In the thirty third preferred embodiment, the power supply cable 129 functions as a radiation plate, and substantially the same effects are produced as in the twenty first preferred embodiment (see FIG. 30). Since the feed circuit board 160 includes the resonance circuit including the inductance elements L11 and L12 and the capacitor, the feed circuit board functions of matching with the radio IC chip 5 and a function of selecting frequency. Thus, signals can be transmitted in a wide range of frequencies. The electromagnetic coupling module 1 may be replaced with only a radio IC chip 5.

Thirty Fourth Preferred Embodiment

In the radio IC device according to thirty fourth preferred embodiment, the resonance circuit provided in the feed circuit board 160 of the electromagnetic coupling module 1 is defined by inductance elements L11, L12 and L13 coupled to each other, as shown in FIG. 46. In the thirty fourth preferred embodiment, the other structure is substantially the same as in the thirty third preferred embodiment, and substantially the same effects are produced as in the thirty third preferred embodiment. In particular, since the resonance circuit is bilaterally symmetrical, the electromagnetic coupling module 1 can be mounted without considering the directivity.

Thirty Fifth Preferred Embodiment

In the radio IC device according to a thirty fifth preferred embodiment, external terminal electrodes 163 and 164 that oppose the internal electrodes 161 and 162 are provided on the rear surface of the feed circuit board 160, as shown in FIG. 47. In the thirty fifth preferred embodiment, the other structure is substantially the same as in the thirty fourth preferred embodiment, and substantially the same effects are produced as in the thirty fourth preferred embodiment. By providing the external terminal electrodes 163 and 164, the electromagnetic coupling module 1 can be bonded on the printed wiring board 120 with solder, for example, and thus, can be mounted simultaneously with other surface mount components.

Thirty Sixth Preferred Embodiment

In the radio IC device according to a thirty sixth preferred embodiment, a power line 122 on which the electromagnetic coupling module 1 is mounted is provided so as to extend a relatively long distance in the lateral direction along an edge of the printed wiring board 120, as shown in FIG. 48. The other structure is substantially the same as in the thirty third preferred embodiment (see FIG. 44). The thirty sixth preferred embodiment produces substantially the same effects as the thirty third preferred embodiment. The lengthened power line 122 can more effectively function as the radiation plate and enables the radio IC device to function before the shielding case 127 or the power supply cable 129 is provided.

Thirty Seventh Preferred Embodiment

The radio IC device according to a thirty seventh preferred embodiment, the extension of the power line 122 shown in FIG. 48 is configured in a meandering arrangement, as shown in FIG. 49. The other structure is substantially the same as in the thirty third preferred embodiment. In the thirty seventh preferred embodiment, the power line 122 functioning as a radiation plate is relatively large, and accordingly, electromagnetic waves can be transmitted and received more efficiently.

Thirty Eighth Preferred Embodiment

In the radio IC device according to a thirty eighth preferred embodiment, the power line 122 shown in FIG. 48 is branched so as to extend a relatively long distance in the lateral direction along an edge of the printed wiring board 120, as shown in FIG. 50. The other structure is substantially the same as in the thirty third and the thirty sixth preferred embodiment. Since the power line 122 functioning as a radiation plate of the thirty eighth preferred embodiment is longer than that of the thirty sixth preferred embodiment, electromagnetic waves can be more efficiently transmitted and received, and the operation can be performed at a low power. Preferably, the power line 122 has a length which enables it to resonate.

Thirty Ninth Preferred Embodiment

In the radio IC device according to a thirty ninth preferred embodiment, the extensions to both sides of the power line 122 are configured in a meandering arrangement, as shown in FIG. 51. The other structure is substantially the same as in the thirty third preferred embodiment. In the thirty ninth preferred embodiment, the power line 122 functioning as a radiation plate is relatively large, and accordingly, electromagnetic waves can be transmitted and received more efficiently.

Fortieth Preferred Embodiment

In the radio IC device according to a fortieth preferred embodiment, a portion of the power line 122 is disposed under the printed wiring board 120, as shown in FIG. 52, and the electromagnetic coupling module 1 is mounted across the region between the power line 122 exposed at the surface and the ground electrode 121. The power supply cable 129 is connected to an end 122 a of the power line exposed at the surface.

In the fortieth preferred embodiment, the other structure is substantially the same as in the thirty third preferred embodiment, and substantially the same effects are produced as in the thirty third preferred embodiment. In particular, since the power line 122 is partially disposed under the printed wiring board 120, the flexibility of wiring on the surface is improved.

Forty First Preferred Embodiment

In the radio IC device according to a forty first preferred embodiment, the power line 122 is bent in a substantial C shape and both ends of the electromagnetic coupling module 1 are connected to the bent portions, as shown in FIG. 53. In the forty first preferred embodiment, the other structure is substantially the same as in the thirty third preferred embodiment, and substantially the same effects are produced as in the thirty third preferred embodiment.

Forty Second Preferred Embodiment

In the radio IC device according to a forty second preferred embodiment, the electromagnetic coupling module 1 is mounted across the power line 122 from one end of the ground electrode 121 to the opposing end, as shown in FIG. 54. The other structure is substantially the same as in the thirty third preferred embodiment, and the electromagnetic coupling module 1 is operated by a difference in potential produced on the ground electrode 121.

In the forty second preferred embodiment, the feed circuit board 160 includes a coil 167 coupled by a magnetic field φ generated by the current flowing in the power line 122 in addition to the inductance elements L11 and L12, as shown in FIG. 55. The coil 167 is connected in series with the inductance elements L11 and L12, and is thus operated by the current flowing in the power line 122. In other words, the coil 167 functions as a matching inductance element. Even if the power line cannot sufficiently receive magnetic waves, the ground electrode 121 can function as a radiation plate, and even if either element of the feed circuit is broken, the other element ensures the operation.

Forty Third Preferred Embodiment

In the radio IC device according to a forty third preferred embodiment, a portion 121 c of the ground electrode 121 coupled to the feed circuit of the electromagnetic coupling module 1 is formed in a loop, as shown in FIG. 56. The other structure is substantially the same as in the thirty third and the forty second preferred embodiment, and substantially the same effects are produced as in the thirty third and the forty second preferred embodiments. By forming the portion 121 c of the ground electrode 121 coupled to the resonance circuit in a loop, the antenna gain is improved, and the radio IC chip 5 can be operated at a low power.

Forty Fourth Preferred Embodiment

In the radio IC device according to a forty fourth preferred embodiment, the ground electrode 121 disposed on the printed wiring board 120 has a relatively large opening 121 b in which a plurality of line electrodes 145 are provided in parallel with each other. The line electrodes 145 are connected to signal lines 146, such as for a USB, and the electromagnetic coupling module 1 is disposed across the region between the ground electrode 121 and one of the line electrodes 145 to be coupled to that one line electrode, as shown in FIG. 57. A regulator 126 is disposed between the line electrodes 145 and the ground electrode 121.

In the forty fourth preferred embodiment, the signal lines 146 function as a radiation plate using the difference in potential between the line electrode 145 and the ground electrode 121, and substantially the same effects are produced as in the thirty third and the twenty ninth preferred embodiment.

Forty Fifth Preferred Embodiment

In the radio IC device according to a forty fifth preferred embodiment, the electromagnetic coupling module 1 is coupled so as to be disposed across the region between two adjacent line electrodes 145, as shown in FIG. 58. The other structure is substantially the same as in the forty fourth preferred embodiment and substantially the same effects are produced as in the forty fourth preferred embodiment. The forty fifth preferred embodiment uses the difference in potential between the two adjacent line electrodes 145.

Forty Sixth Preferred Embodiment

In the radio IC device according to a forty sixth preferred embodiment, the ground electrode 121 disposed on the printed wiring board 120 includes a slit opening 121 a, as shown in FIG. 59. An antenna line 151 is disposed in the slit opening 121 a, and an antenna wire 152 is connected to the antenna line 151. The electromagnetic coupling module 1 is coupled so as to be disposed across a region between the antenna line 151 and the ground electrode 121. The regulator 126 is disposed between the antenna line 151 and the ground electrode 121. In the forty sixth preferred embodiment, the antenna wire 152 functions as the radiation plate, and substantially the same effects are produced as in the thirty third and the thirtieth preferred embodiment.

Forty Seventh Preferred Embodiment

In the radio IC device according to a forty seventh preferred embodiment, an auxiliary substrate 170 is provided on which the electromagnetic coupling module 1 is mounted, as shown in FIG. 60. A coupling electrode 171 is provided on the auxiliary substrate 170, and a pair of loop electrodes 173 functioning as inductance elements is provided for the coupling electrode 171. The electromagnetic coupling module 1 (or radio IC chip 5 alone) is coupled to each end of the loop electrodes 173. The ends of the coupling electrode 171 are connected to the power line 122 and the ground electrode 121 with solder 175. The other structure is substantially the same as in the thirty third preferred embodiment.

In the forty seventh preferred embodiment, the electromagnetic coupling module 1 is coupled to the loop electrodes 173, and in addition, the coupling electrode 171 is disposed across the region between the power line 122 and the ground electrode 121 so as to be coupled to the power line 122 and the ground electrode 121. Thus, substantially the same effects are produced as in the thirty third preferred embodiment. In particular, the use of the auxiliary substrate 170 enables even a small electromagnetic coupling module 1 to be disposed across the region between the power line 122 and the ground electrode 121. In addition, an inductance element or other suitable element may be provided on the auxiliary substrate 170 in order to reduce the size of the feed circuit board 160. Furthermore, the coupling electrode 171 on the auxiliary substrate 170 functions as a radiation plate by itself.

Forty Eighth Preferred Embodiment

In the radio IC device according to a forty eighth preferred embodiment, an anti-ESD device, such as a varistor 153, for example, is disposed between the power line 122 and the ground electrode 121, and an electromagnetic coupling module 1 is disposed downstream from the varistor 153, as shown in FIG. 61. The other structure is substantially the same as in the thirty third preferred embodiment (see FIG. 44). The forty eighth preferred embodiment produces substantially the same effects as the thirty third and the thirty first preferred embodiment.

Forty Ninth Preferred Embodiment

In the radio IC device according to a forty ninth preferred embodiment, a ground electrode 181 disposed on a printed wiring board 180 includes an opening 182 to define a loop electrode 183, and the electromagnetic coupling module 1 is mounted on the loop electrode 183, as shown in FIG. 62. The electromagnetic coupling module 1 includes the radio IC chip 5 and a feed circuit board 190. The feed circuit board 190 includes a coil (inductance element) 191, as shown in FIG. 64. The coil 191 is arranged such that the coil axis extends parallel or substantially parallel to the loop electrode 183, and each end of the coil 191 is electrically connected to the radio IC chip 5.

In the operation principle of the radio IC device of the forty ninth preferred embodiment, when the ground electrode 181 receives magnetic waves from a reader/writer (not shown), the loop electrode 183 generates a current. The magnetic field φ generated by the current is coupled to the coil 191 of the feed circuit board 190, thus operating the radio IC chip 5. In this instance, preferably, the electromagnetic coupling module 1 is arranged such that a magnetic field φ intersects only one side of the coil 191. In addition to the coil 191, a matching circuit/resonance circuit 192 may be provided within the feed circuit board 190, as shown on FIG. 65.

The elements 105, 106 and 107 disposed on the printed wiring board 180 are substantially the same as in the fifteenth preferred embodiment (see FIG. 23).

Fiftieth Preferred Embodiment

In the radio IC device according to a fiftieth preferred embodiment, the loop electrode 183 provided on the ground electrode 181 is bent in a substantial C shape, and the electromagnetic coupling module 1 is mounted such that the coil 191 is disposed along the loop electrode 183, as shown in FIG. 66. The other structure is substantially the same as in the forty ninth preferred embodiment.

The fiftieth preferred embodiment produces substantially the same effects as the forty ninth preferred embodiment. In particular, the degree of coupling between the coil 191 and the loop electrode 183 is improved and the energy can be efficiently transmitted. In addition, the electromagnetic coupling module 1 does not significantly protrude from the edge of the printed wiring board 180.

Fifty First Preferred Embodiment

In the radio IC device according to a fifty first preferred embodiment, the electromagnetic coupling module 1 is disposed in a reverse orientation to that in the forty ninth preferred embodiment (see FIG. 62) on the printed wiring board 180, as shown in FIG. 67. The other structure is substantially the same as in the forty ninth preferred embodiment, and substantially the same effects are produced as in the forty ninth preferred embodiment. In particular, it is an advantage that the electromagnetic coupling module 1 does not significantly protrude from the edge of the printed wiring board 180.

Fifty Second Preferred Embodiment

In the radio IC device according to a fifty second preferred embodiment, the feed circuit board 190 includes a coil 191 arranged such that the coil axis extends perpendicular or substantially perpendicular to the loop electrode 183, as shown in FIG. 68. The fifty second preferred embodiment produces substantially the same effects as the forty ninth preferred embodiment. In particular, the coil 191 is arranged such that the coil axis extends in the direction in which the sheets of the feed circuit board 190 are stacked, and this facilitates the formation of the coil 191.

Fifty Third Preferred Embodiment

In the radio IC device according to a fifty third preferred embodiment, the electromagnetic coupling module 1 is mounted at an edge of the ground electrode 181 without providing a loop electrode 183 on the ground electrode 181, as shown in FIG. 69. The other structure is substantially the same as in the forty ninth preferred embodiment, and substantially the same effects are produced as in the forty ninth preferred embodiment. The electromagnetic coupling module 1 is operated by being coupled with a magnetic field generated by the current flowing in the edge of the ground electrode 181.

Fifty Fourth Preferred Embodiment

In the radio IC device according to a fifty fourth preferred embodiment, a notch 184 is provided in the printed wiring board 180, and the ground electrode 181 includes a loop electrode 183 at the edge around the notch 184, as shown in FIG. 70. The other structure is substantially the same as in the forty ninth preferred embodiment, and substantially the same effects are produced as in the forty ninth preferred embodiment.

Fifty Fifth Preferred Embodiment

In the radio IC device according to a fifty fifth preferred embodiment, the electromagnetic coupling module 1 is arranged in a corner of the ground electrode 181 as shown in FIG. 71, unlike the fifty third preferred embodiment in which the electromagnetic coupling module 1 is disposed substantially at the center of an edge of the ground electrode 181. The other structure is substantially the same as in the forty ninth and the fifty third preferred embodiment, and substantially the same effects are produced as in the forty ninth and fifty third preferred embodiment.

If the ground electrode 181 does not include the loop electrode 183, the electromagnetic coupling module 1 can be disposed anywhere on the edge of the ground electrode 181. Alternatively, a notch may be provided in the corner of the printed wiring board 180 on which the electromagnetic coupling module 1 is disposed, as disclosed in the fifty fourth preferred embodiment, and the ground electrode 181 has a loop electrode at the edge around the notch.

Fifty Sixth Preferred Embodiment

In the radio IC device according to a fifty sixth preferred embodiment, a coil 195 in a feed circuit board 190 has a substantial FIG. 8 shape, as shown in FIG. 72, and the other structure is substantially the same as in the forty ninth preferred embodiment (see FIG. 62). The electromagnetic coupling module 1 is arranged on the printed wiring board 180 such that the magnetic flux φ generated from the loop electrode 183 can pass through the loops of the coil 195 functioning as inductance elements, as shown in FIG. 73. In the fifty sixth preferred embodiment, consequently, the ground electrode 181 functioning as a radiation plate and the electromagnetic coupling module 1 can be highly coupled.

Modification of Electromagnetic Coupling Module

The electromagnetic coupling module 1 may preferably include a square feed circuit board 200, as shown in FIG. 74. The coil 201 functioning as an inductance element also has a square shape. This electromagnetic coupling module 1 can be applied to any preferred embodiment of the present invention.

Fifty Seventh Preferred Embodiment

In the radio IC device according to a fifty seventh preferred embodiment, a slit 185 is provided in the ground electrode 181 disposed on the printed wiring board 180, extending from the edge to the approximate center. The slit 185 has an opening 185 a at the end thereof, and the electromagnetic coupling module 1 is disposed over the opening 185 a, as shown in FIG. 75. The coil 191 provided on the feed circuit board 190 and the opening 185 a have substantially the same shape in plan view.

In the fifty seventh preferred embodiment, the surrounding of the opening 185 a functions as a loop electrode to be magnetically coupled to the coil 191. The presence of the slit 185 improves the concentration of the current produced by the electromagnetic waves received by the ground electrode 181 around the opening 185 a to generate a strong magnetic field, thus improving the degree of coupling.

The slit 185 does not necessarily communicate with the edge of the ground electrode 181. If the slit 185 is to be arranged according to the design of the printed wiring board 180, another slit is not necessarily provided for the electromagnetic coupling module 1.

In the radio IC device according to preferred embodiments of the present invention, the feed circuit board may preferably have a resonance circuit through which the radio IC is operated by the signal received by the radiation plate, and through which the answer signal from the radio IC is radiated from the radiation plate to the outside. The feed circuit board may include a matching circuit.

The inductance element may preferably be defined by a spiral electrode, for example, and the spiral electrode may be coupled with a magnetic field generated at the wiring electrode on the wiring board. The wiring electrode and the ground electrode on the wiring board may be isolated from each other, and the feed circuit board may be disposed across a region between the wiring electrode and the ground electrode. If the case is a metal, the case may function as a radiation plate by itself. If the case is non-conductive, an electroconductive electrode film may be formed on the case and the electrode film is used as the radiation plate.

The printed wiring board may preferably include an electromagnetic coupling module and other electronic components, and a case also defining the radiation plate is disposed so as to cover the high frequency device and other electronic components. The printed wiring board may include a second wiring electrode for coupling the feed circuit and the radiation plate. In particular, if the second wiring electrode is in a loop, the impedances can be matched between the radio IC and the radiation plate without providing an additional matching portion, and the signal transmission efficiency can be improved between the radio IC and the radiation plate. The loop electrode may be formed in an auxiliary substrate disposed on the feed circuit board. A plurality of printed wiring boards may be used, and a high frequency device is disposed on at least one of the printed wiring boards. A case may be arranged so as to cover the high frequency device and at least one of other electronic components.

The printed wiring board may include a second wiring electrode arranged to couple the feed circuit and the radiation plate, and a case may be arranged so as to cover all the electronic components and high frequency device mounted on the printed wiring board. The second wiring electrode may function as a portion of the radiation plate. In this instance, the radiation characteristics can be improved, and the directivity can be changed depending on the arrangement of the second wiring electrode. At least a portion of the electronic components may function as a portion of a radiation plate to improve the radiation characteristics.

The printed wiring board may include a ground electrode, and a second wiring electrode may be electrically connected to the ground electrode. By using the ground electrode having a large area as a radiation plate, the radiation characteristics can further be improved.

The second wiring electrode may be provided on the surface of or within the printed wiring board. The printed wiring board may be made of a resin or a ceramic, for example.

An external electrode coupled to the feed circuit may be formed on the surface of the feed circuit board.

The feed circuit board may be made of a ceramic or liquid crystal polymer multilayer substrate, or a flexible substrate, for example. The use of a multilayer substrate enables an inductance element or a capacitance element to be arranged precisely within the feed circuit board, thus improving the flexibility in the formation of electrodes. The use of a flexible substrate facilitates the reduction of the thickness or profile of the feed circuit board.

The radio IC may be rewritable as well as storing information of the commodity on which the radio IC device is attached, and may have other functions in addition to the function for an RFID system.

The radio IC device according to the present invention is not limited to the above-described preferred embodiments, and various modifications may be made without departing from the scope of the present invention.

For example, various types of resonance circuit or matching circuit may be used. The materials used for the external electrode and the feed circuit board in the above-described preferred embodiments are described as examples, and any material can be used as long as it has desired properties. The radio IC chip can be mounted on the feed circuit board by any method other than using a metal bump. The radio IC chip and the feed circuit may be connected by electromagnetic coupling instead of electrical direct connection. The feed circuit board may include a radio IC.

The electromagnetic coupling module may be used in a variety of apparatuses including household electrical appliances, such as TV set and refrigerator, without being limited to radio communication apparatuses, such as cellular phone.

As described above, the present invention is useful in radio IC devices used in RFID systems, and is particularly advantageous in miniaturization without reducing the radiation characteristics.

While preferred embodiments of the present invention have been described above, it is to be understood that variations and modifications will be apparent to those skilled in the art without departing the scope and spirit of the present invention. The scope of the present invention, therefore, is to be determined solely by the following claims. 

What is claimed is:
 1. A radio IC device comprising: a radio IC arranged to process transmitted and received signals; a coil element electrically connected to or electromagnetically coupled to the radio IC; and a radiation plate arranged so as to be coupled to the coil element; wherein the radiation plate is defined by a metal case of an apparatus, and a loop electrode defined by an edge of an opening in a planar portion of the metal case is provided in a portion of the metal case; the coil element is coupled to the loop electrode of the metal case via a magnetic field; and the metal case functions as the radiation plate such that the transmitted signals processed by the radio IC are radiated from the metal case and the received signals received by the metal case are processed by the radio IC.
 2. The radio IC device according to claim 1, wherein the radiation plate includes a notch provided therein, and an edge of the radiation plate which is located around the notch defines the loop electrode.
 3. The radio IC device according to claim 1, wherein the coil element is defined by a spiral electrode.
 4. A radio IC device comprising: a radio IC arranged to process transmitted and received signals; a coil element electrically connected to or electromagnetically coupled to the radio IC; and a radiation plate arranged so as to be coupled to the coil element; wherein the radiation plate is defined by a planar metal case of an apparatus; the coil element is provided adjacent to an edge of the planar metal case such that one portion of the coil element overlaps with the edge of the planar metal case in planar view and another portion of the coil element is arranged outside of the planar metal case in planar view, and coupled to the planar metal case via a magnetic field generated by current flowing in the edge of the planar metal case; and the planar metal case functions as the radiation plate such that the transmitted signals processed by the radio iC are radiated from the the radio IC.
 5. The radio IC device according to claim 4, wherein the coil element is defined by a spiral electrode. 